Category Archives: .NET

Fast shared Array, Buffer and Circular Buffer / Ring Buffer for .NET IPC with Memory Mapped Files

About the SharedMemory library

The SharedMemory class library provides a set of C# classes that utilise a non-persisted memory-mapped file for very fast low-level inter-process communication (IPC) to share data using the following data structures: buffer, array and circular buffer (also known as a ring buffer).

SharedMemory uses the MemoryMappedFile class introduced in .NET 4, and provides a partial P/Invoke wrapper around the Windows API for versions prior to this. The library was originally inspired by the following CodeProject article: “Fast IPC Communication Using Shared Memory and InterlockedCompareExchange“.

The library abstracts the use of the memory mapped file, adding a header that includes information about the size of the shared memory region so that readers are able to open the shared memory without knowing the size before hand. A helper class to support the fast copying of C# fixed-size structures in a generic fashion is also included.

The project source can be found on GitHub, with binaries available via Nuget.

What is a memory mapped file?

A memory-mapped file is an area of virtual memory that may have been mapped to a physical file and can be read from and written to by multiple processes on the same system. The file or portions thereof are accessed via views to one or more processes as a contiguous block of memory. Each view can then be read/written to using a memory location.

A memory-mapped file can be created as one of two types:

  • persisted: mapped to a physical file, and
  • non-persisted: in-memory only,  commonly used for inter-process communication (IPC).

A memory-mapped file is referenced using a unique name, unlike named pipes however a memory-mapped file cannot be accessed directly over a network.

Continue reading Fast shared Array, Buffer and Circular Buffer / Ring Buffer for .NET IPC with Memory Mapped Files

x86/x86-64 Disassembler for .NET – SharpDisasm

About the disassembler

SharpDisasm is a full C# port of the libudis86 x86/x86-64 disassembler. Disassembly of 16-bit, 32-bit and 64-bit instructions can be output to both Intel and AT&T syntax.

The library supports decoding each instruction to an object that provides access to low-level information for further analysis (e.g. instruction size, operand number and types etc).

SharpDisasm is a full C# port of the libudis86 C-library disassembler.

Disassembler features

  • a full C# port of the libudis86 C library
  • a set of simple C# classes wrapping the udis86 C API
  • support for x86 16-bit, 32-bit and 64-bit instruction set architectures
  • support for outputting in Intel and AT&T syntax
  • support for all x86 and x86-64 (AMD64) General purpose and System instructions.
  • support for the following ISA extensions:
    • MMX, FPU (x87), AMD 3DNow
    • SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AES

The disassembler is exposed through the SharpDisam.Disassembler class.

Output from the provided example console app:

C:\>echo a1 c9 fd ff ff a1 37 02 00 00 b8 37 02 00 00 b4 09 8a 
25 09 00 00 00 8b 04 6d 85 ff ff ff 89 45 f0| disasmcli 32

00000000 a1 c9 fd ff ff mov eax, [0xfffffdc9]
00000005 a1 37 02 00 00 mov eax, [0x237]
0000000a b8 37 02 00 00 mov eax, 0x237
0000000f b4 09 mov ah, 0x9
00000011 8a 25 09 00 00 00 mov ah, [0x9]
00000017 8b 04 6d 85 ff ff ff mov eax, [ebp*2-0x7b]
0000001e 89 45 f0 mov [ebp-0x10], eax

C:\>echo 488b05f7ffffff67668b40f06766035e1048030425ffff
000067660344bef04c0384980000008048a10000000000800000 | disasmcli 64

0000000000000000 48 8b 05 f7 ff ff ff mov rax, [rip-0x9]
0000000000000007 67 66 8b 40 f0 mov ax, [eax-0x10]
000000000000000c 67 66 03 5e 10 add bx, [esi+0x10]
0000000000000011 48 03 04 25 ff ff 00 00 add rax, [0xffff]
0000000000000019 67 66 03 44 be f0 add ax, [esi+edi*4-0x10]
000000000000001f 4c 03 84 98 00 00 00 80 add r8, [rax+rbx*4-0x80000000]
0000000000000027 48 a1 00 00 00 00 00 80 00 00 mov rax, [0x800000000000]


Download source from GitHub or download binaries on NuGet.